Bayern Munich fell 3-2 to Napoli in the final match of the Bavarians' pre-season training camp on the banks of Lake Garda in Italy on Friday.
Napoli succeeded where it had twice failed in last season's UEFA Champions League group phase, having been held to a 1-1 draw at home before losing 3-2 in the return match in Munich.
Young Austrian David Alaba opened the scoring for beaten Champions League finalist Bayern in the 17th minute, with Paolo Cannavaro equalising shortly before half-time.
New signing Xherdan Shaqiri equalised for Bayern after Macedonian striker Goran Pandev had put Napoli 2-1 up, only for 21-year-old forward Lorenzo Insigne to claim the winner for the Serie A side with seven minutes remaining.
Bayern was missing its eight German internationals, who are still on holiday after EURO 2012, as well as France winger Franck Ribery, who has resumed pre-season training on his own in Munich.
Jupp Heynckes' side will fly to China for two friendly matches: against Beijing Guoan in Beijing on July 24 and then Wolfsburg in Canton on July 26.
Bayern Munich sets out to weaken its domestic competition, said Borussia Dortmund CEO Hans-Joachim Watzke.